The PON system is more and more widely applied in the field of communications, therefore, services installation, acceptance test, and routine maintenance of a PON device and an optical fiber network also increase. An OTDR can play an important role in aspects such as testing, fault positioning and removal, and so on of the PON system. Therefore, how to better utilize the OTDR to improve maintenance efficiency of a passive optical network has a significant and positive meaning.
When the OTDR is used for detection of the PON system, a data transmitter may be shared to send an OTDR test signal. For example, in normal communications, a laser diode (LD) sends a data signal; and when a test is performed, a test signal is superposed on the data signal and the superposed signal is transmitted through the LD, and a reflected signal corresponding to the test signal is returned to an OTDR receiver for processing. Accordingly, the PON system is ensured to maintain a communication status during the OTDR test.
To implement sharing the data transmitter to send the OTDR test signal, in the prior art, the OTDR test signal is used to control a modulation current of an LDD (Laser Diode Drive) on the data signal. By adjusting the modulation current of the LDD, optical power of the laser diode is controlled to output a test waveform, so as to modulate the OTDR test signal to the data signal. However, a modulation bandwidth of the modulation current of the LDD is very small. As a result, a rate of the OTDR test signal is limited, and furthermore, a spatial resolution of the test of the OTDR is low. Therefore, quality of the OTDR test signal is poor.